To support high capacity demand and new applications in evolving networks such as fifth generation (5G) wireless networks, ultra-dense networks (UDN) and moving networks (MN) are being developed. Such network architectures are challenged by high capacity demand, severe inter-cell interferences, frequent handovers, and fast moving users, among other challenges. Technologies such as Coordinated multipoint (CoMP) or Joint transmission (JT) CoMP, Coordinated beam forming/scheduling (CB/CS) CoMP, and multi-user multiple-input and multiple-output (MU-MIMO) based on beam forming are being proposed to alleviate such challenges. However, such CoMP and MU-MIMO schemes are closed-loop schemes, requiring channel state information (CSI) feedback with high overhead. The CSI feedback is also sensitive to channel aging and feedback error. Sparse Code Multiple Access (SCMA) is a transmission scheme with relatively low complexity receiver design and good performance. SCMA can offer high spectral efficiency by supporting overloaded systems having more connected devices or traffic than orthogonal resources. A Multi-user SCMA (MU-SCMA) scheme can also increase throughput and coverage, and support open-loop (OL) user multiplexing with low feedback overhead and with less sensitivity to channel aging and feedback error.
However, there is still a need for more efficient CoMP systems.